There are those who believe the dangers from "swine flu" (H1N1) in 2009 and Sars in 2003 were exaggerated by "mad scientists". It's true that, thankfully, swine flu and Sars have not so far proved as devastating as originally feared, but before the next emerging human infection hits the headlines, pandemic sceptics should find time to read The Viral Storm by a Stanford virologist called Nathan Wolfe.

This is a tale of ever-increasing intimacy between ourselves and other animal species: the source of pathogens that the human immune system has never encountered before. Wolfe traces the origin of humanity's exceptional susceptibility to these novel pathogens back millions of years to when the common ancestor we share with chimpanzees developed a taste for monkey meat.

"We tend to think of events like sex or childbirth as intimate, and they certainly bring together individuals in ways that normal interactions cannot. But from the perspective of a microbe, hunting and butchering represent the ultimate intimacy, a connection between one species and all of the various tissues of another, along with the particular microbes that inhabit each one of them."

So while others date the start of the HIV pandemic to the 1980s, for Wolfe it began 8m years earlier when the forest-dwelling ancestor of humans and chimpanzees began to hunt and butcher monkeys. The DNA of viruses from the red-capped mangabey and the greater spot-nosed guenon are then thought to have mingled in a chimpanzee to create a completely new virus, which eventually jumped to human hunters early in the 20th century.

Wolfe's history of increasing intimacy between humans and other species continues with the domestication of animals around 10,000 years ago. This not only provided the ready source of protein that would allow former hunter gatherers to settle down in large, sedentary communities, it also meant close and sustained contact with the pigs, cattle, chickens and goats that would act as "microbial bridges" between wild animals and people.

And finally, of course, came the boats, cars, trains and planes that have connected every human population on Earth with every other. The whole world has become a single microbial incubator, says Wolfe.

Medical science may have come to our aid with hugely successful vaccines against established human pathogens such as smallpox, but at the same time, the 20th century technologies of transfusion, transplantation and injection "have connected us with one another's blood, organs, and other tissues in ways unprecedented in the history of life on our planet".

The ancient channels of transmission from animal to human remain open, because there are communities in central Africa that still rely heavily on bushmeat. Meanwhile, at the other end of the scale, industrial livestock farming has increased still further the opportunities for pathogens to adapt and make the leap into humans.

Wolfe has an important story to tell and as a virologist at the forefront of pandemic forecasting, he is the perfect person to tell it. He explains the science clearly and never stoops to sensationalism – the evidence of our increasing vulnerability to pandemics speaks for itself.

But this would be a grim story indeed if it ended there. Wolfe remains surprisingly upbeat, however, because while the threat of pandemics has grown, the tools to predict and monitor them have in the past decade become very sophisticated. Our weapons against future pandemics are rapid DNA sequencing, microarrays and labs on chips, and "digital epidemiology" – sifting through the profusion of clues about emerging diseases available in mobile phone calling patterns, electronic medical records and the digital chatter of Google and Twitter.

Control centres to predict future pandemics, such as Wolfe's own Global Viral, are being established. They can't track every infection on the planet, but they can closely monitor the "sentinels" – groups of people vulnerable to infections from other species, such as bushmeat hunters in Central Africa, and individuals whose jobs mean they can spread infections widely, such as aircraft cabin crew and medical staff.

The ultimate objective is a "global immune system" for forecasting and preventing pandemics. For those who read Wolfe's book to the end but still baulk at the cost of such a system, his closing chapter contains a telling statistic.

Around 8,000 people died worldwide at the hands of terrorists between April 2001 and August 2002, a period that included the 9/11 attacks. Between April 2009 and August 2012, more than 18,000 died as a result of H5N1. Shouldn't we spend at least as much on preventing pandemics as we spend in the war on terror?